Edging devices are used to form a trench around the periphery of a landscape area to establish a line of demarcation between the landscape areas. For example, where lawns are adjacent to beds with flowers and/or bushes, and/or surround trees, a distinct dividing line can be formed around the periphery of the bed to create a distinct line of demarcation with respect to the lawn. Commonly, this line is defined by cutting a trench with a vertical wall at the edge of the lawn area. This trench restricts the spreading of grass from the lawn to the adjacent beds and also produces an aesthetically pleasing, sharp, dividing line between the different types of landscape.
The formation of these trenches around the periphery of landscape beds is commonly referred to as edging. Edging has been done in years past with conventional hand tools, such as flat-bladed shovels. While manual formation of trenches is desirable from a standpoint of flexibility and control, forming the trenches manually is labor intensive, requiring at least one worker slowly forming the trench. Thus, the manual formation of the landscape edging has a number of drawbacks. The slow manual formation of the edging trench typically requires the investment of many man hours, which typically dictates the need for a large work crew. This manual formation of the edging trench can be onerous when the work crew encounters dry and hard ground conditions, leading to significant worker fatigue. Furthermore, the manual formation of the edging trench usually results is an overall ragged appearance that does not precisely follow an intended course due to the incremental formation of the trench. Also, workers must deal with the material removed during trench formation. In a typical formation using a shovel, large chunks of terrain may be separated. These chunks either have to be hauled away or broken up manually to be distributed back into the bed.
As is shown in U.S. Pat. No. 2,555,441, granted on Jun. 5, 1951, to James G. Hackney, and in U.S. Pat. No. 2,737,105, granted on Mar. 6, 1956, to Aaron Wilson, edgers with powered rotating cutting assemblies have been developed for use in the landscaping industry to replace the manual process of forming edging trenches. Some edger cutting systems, such as disclosed in U.S. Pat. No. 6,857,481, issued to Johnny Hayes on Feb. 22, 2005, and in U.S. Pat. No. 6,092,608, granted on Jul. 25, 2000, to Herbert J. Leger, have a rotary, generally flat disc-shaped blade that penetrates the ground to produce an edging trench with spaced vertical walls. Such an edging device will cut large chunks of terrain that have to be either hauled away or broken up to be distributed back into the landscape bed.
In U.S. Pat. No. 4,002,205 issued on Jan. 11, 1977, to David C. Falk, and in U.S. Pat. No. 5,355,597, issued to Charles H. Pollard on Oct. 18, 1994, the powered trench cutting system is provided with a welded cutting member that includes a series of teeth strategically disposed to cooperatively produce a beveled or v-shaped trench. The toothed trench-forming blade in U.S. Patent Publication No. 2004/0251037 of David J. Templeton, published on Dec. 16, 2004, pulverizes the terrain that is removed from forming the trench and piles the removed terrain along the side of the trench to be manually distributed back into the bed without the need to be hauled away.
Both powered cutting systems have a frame structure with one or more wheels that facilitate controlled repositioning the edging apparatus over an adjacent surface of the ground. The operator can either manually pull the less expensive non-self-propelled version of the edging machine backwards along the periphery of the landscape bed to form the edging trench or the operator can walk forwardly when operating a more expensive self-propelled configuration of the edging machine, such as is disclosed in U.S. Pat. No. 5,156,218, granted to Dennis E. Metzler, et al, on Oct. 20, 1992.
While both of these types of powered cutting edgers overcome problems associated with manual trenching, the use of such powered edging devices also has some limitations and drawbacks.
First of all, the pull-backward edging machines, such as is disclosed in U.S. Pat. No. 7,096,970, granted on Aug. 29, 2006, to Roger D. Porter, et al, require the operator to pull the machine rearward, which is opposite to the direction that the blade rotation is trying to push the machine as the trench is being formed. Fighting the rotation of the cutting assembly causes premature operator fatigue. A similar problem is associated with the forward operating self-propelled machine, such as is disclosed in U.S. Pat. No. 6,883,616, issued on Apr. 26, 2005, to David J. Templeton, as this machine also has a cutting blade that pushes the machine in the opposite direction that the drive mechanism for the machine is moving the machine, thereby wasting engine power with opposing forces fighting against each other.
Both self-propelled and non-self-propelled trench forming machines are typically heavy implements, weighing between 125 and 400 pounds, which can cause transportation problems, particularly for rental centers, as the implement would require two or more people to lift the implement. These machines have a cutting system that utilizes multiple tooth blunt cutting blades to form the trench. When these blunt cutting blades encounter hard soil, tree roots and rocks, the rotation of the cutting system tends to raise the machine which tends to make the machine buck and jump relative to the ground. The solution to this problem is to make the machine heavy enough to keep the machine under control. Furthermore, these blunt tooth cutting systems have a cutting geometry that doesn't allow the cutter to slide up and over obstructions, as the teeth bite into the obstruction which magnifies the bucking and jumping problem.
Additional problems associated with the conventional powered edging machines is that for the non-self-propelled version, the machine is difficult to operate as the machine has to be pulled rearwardly forcing the operator to look rearwardly in order to walk, while being required to look forwardly to observe the machine cutting the edging trench. Accordingly, the non-self-propelled machine is uncomfortable and non-intuitive to operate. In the conventional powered cutting system, the throw path geometry of the pulverizing cutting blade soil distribution system throws the displaced terrain upwardly from the blade into engagement with a deflecting shield that first deflects the soil laterally and then deflects the soil downwardly to pile the soil along the side of the edging trench being formed. This displaced soil will need to be hand raked and spread out into the landscape bed, or alternatively removed, which requires an additional manual operation.
The problem of bucking a jumping of the machine when encountering obstacles is worse when the trench forming machine is pushed forwardly instead of being pulled backwardly. The operator can quickly lose control of the conventional trench forming machine when pushing in the same direction that the blunt cutting teeth of the rotor are pushing. Accordingly, the operator will have difficulty reacting quickly enough to change direction of the movement of the machine when an obstacle is encountered by the blunt teeth. By the time the operator realized an obstacle has been encountered, the trench forming machine has already thrust forwardly and possibly bucked sideways, thereby cutting in an unintended trench cutting path. Therefore, pulling conventional trench forming machine rearwardly puts the operator in a better position to react and maintain control of the operation of the machine since the operator is pulling the edger rearwardly.
Another problem associated with conventional powered trench cutting systems is the throw path geometry for the displaced soil from the edging trench. This pulverizing cutting blade soil distribution system does not deflect all of the displaced soil onto the bed adjacent the trench being formed. During the movement of the displaced, pulverized soil upwardly from the cutting blade, some of the soil will deflect out of the soil deflecting structure and land on the grass side of the trench. The unintentional displacement of the soil landing on the uncut grass terrain gives an un-finished look to the edging trench, which again requires re-distribution (clean-up) by hand-raking it over the edging trench and into the landscape bed through an additional manual operation.
The displaced soil throw path geometry of the pulverizing cutting blade soil distribution system on conventional powered cutting systems can have difficulty operating properly in wet soil conditions. Wet soil may cling and build up to the deflecting shields to a point of plugging the soil distribution throw path. When the throw path is plugged, the wet soil will build-up on the deflecting shields, which will then release as clumps of soil that later have to be broken up, then raked by hand into the bed in an additional operation. Alternatively, the wet soil will eventually accumulate on the deflecting shield to a point the deflecting shield completely plugs the machine, preventing any cut soil from being distributed from the cutting blade, which results in stoppage of the edging operation.
Conventional powered cutting systems, such as disclosed in U.S. Pat. No. 7,806,196, granted to Brent Peterson on Oct. 5, 2010, utilize blunt cutting teeth that pound the ground to penetrate, and then bulldozes through the terrain to displace soil and form the edging trench. Cutting an edging trench in such a blunt force operation requires excessive engine power, which is particularly onerous when the ground conditions are dry and hard. Furthermore, this blunt force type of cutting system also demands a heavy duty, and thus more expensive, drive mechanism to power the cutting blade. In addition, this blunt force trench cutting system requires the cutting blades to be disposed in a manner to produce a beveled or V-shaped edging trench. The blunt cutting teeth catch on every rock and tree root that might lie under the surface of the ground where the edging trench is to be formed. When the blunt cutting teeth hit on such obstructions, the teeth try to cut through the obstruction (possibly damaging the tree roots), but there is a tendency for the edger to “jump” randomly from the terrain during operation, potentially causing damage to the machine, injury to the operator, and imprecise trench formation, or at a minimum slow or even stop the edging operation.
The formation of a beveled or V-shaped edging trench requires the conventional powered trench cutting systems to orient the axis of rotation of the cutting implement somewhat parallel to the terrain surface. In some topographical circumstances, orienting the axis of rotation parallel to the ground results in a long reach for the extended cutting teeth to reach the surface of the ground past the bearing support structure, and then penetrate the cut distance into the terrain to reach the desired trench depth. The further the cutting teeth are from the bearing support, the longer the moment arm distance is away from the axis of rotation of cutting implement, which results in requiring more torque/power to form the edging trench.
Furthermore, the large soil deflecting structure needed for the conventional powered trench cutting systems to try to control the displacement of the soil from the edging trench being formed restricts the view of the operator and limits the ability of the operator to place the formation of the edging trench at exactly the location desired. Although the large soil deflecting shield is needed on conventional machines to deflect the displaced soil onto the bed adjacent the edging trench being formed and to prevent injury to the operator and others from flying debris, the large box shape of the soil deflecting shield is completely encloses the cutting blade system, which doesn't allow the operator good visibility to see where the blade is cutting the terrain.
Accordingly, it would be desirable to provide an apparatus for cutting an edging trench around landscape beds that had an improved system for displacing soil from the trench onto the ground adjacent the formed trench. It would also be desirable to provide a trench forming apparatus in which the cutting member was rotated in a direction that would facilitate the movement of the apparatus over the surface of the ground during operation in forming the edging trench.